The present invention relates to an apparatus and method for locating and positioning a medical device in a patient""s body. In particular, the present invention relates to a catheter based drug delivery device having ultrasound imaging technology that facilitates tracking of the catheter as it is maneuvered through the body of a patient.
The number and variety of medical device and methods available to repair the effects of cardiovascular disease has increased rapidly over the last several years. More particularly, alternatives to open heart surgery and cardiovascular by-pass surgery have been extensively investigated, resulting in non-surgical procedures such as Percutaneous Transluminal Coronary Angioplasty (PTCA), Percutaneous TransMyocardial Revascularization (PTMR) and gene therapy. These procedures are primarily directed toward the reduction of stenosis within the vasculature of a patient or the generation of new blood vessels in the body for restoring blood flow to tissues after injury or trauma.
In general, PTCA is a catheter-based technique whereby a balloon catheter is inserted into the blocked or narrowed coronary lumen of a patient. Once the balloon is positioned at the target site, the balloon is inflated causing dilation of the lumen. The catheter is then removed from the target site thereby allowing blood to freely flow through the unrestricted lumen.
Although PTCA procedures aid in alleviating intraluminal constrictions, such constrictions or blockages reoccur in many cases. The cause of these recurring obstructions, termed restenosis, is due to the body responding to the trauma of the surgical procedure. As a result, drug therapies are often applied in combination with the PTCA procedure to avoid or mitigate the effects of restenosis at the surgical site. The drugs are delivered to the site via a needle housed within the catheter. The term xe2x80x9cdrug(s),xe2x80x9d as used herein, refers to all therapeutic agents, diagnostic agents/reagents, genetic materials, growth factors, angiogcnic substances and other similar chemical/biological agents or fluids, including combinations thereof used to treat and/or diagnose restenosis, thrombosis, angiogenesis and related conditions.
Other procedures, such as those developed to control the effects and occurrence of angiogenesis, also utilize a catheter for delivering drugs to diseased vessels and ischemic myocardium. Angiogenesis is a process whereby new blood vessels are grown in the body for healing wounds and for restoring blood flow to tissues after injury or trauma. Angiogenesis occurs naturally in the body, both in health and in disease states. For example, in females, angiogenesis occurs during the monthly reproductive cycle to rebuild the uterus lining and to mature the egg during ovulation. In addition, angiogenic growth factors are also present during pregnancy to build the placenta and create the vessels necessary for circulation between the mother and fetus.
Angiogenesis also occurs in various disease states, such as cancer, diabetic blindness, age-related macular degeneration, rheumatoid arthritis, coronary artery disease, stroke, and other disorders. In cases of excessive angiogenesis, the new blood vessels feed diseased tissues, destroy normal tissues and, with respect to cancer, allow tumor cells to escape into the circulation and lodge in other organs. Conversely, insufficient angiogenesis causes inadequate blood vessel growth thereby impeding circulation which, in turn, potentially leads to tissue death.
Although angiogenesis occurs naturally in the body, various procedures have been developed to artificially control the occurrence and effects of angiogenesis. One such procedure is Percutaneous TransMyocardial Revascularization (PTMR). PTMR utilizes a laser catheter to create small channels in the diseased tissue. The channels re-establish direct blood flow to the tissue and allow oxygen-rich blood to saturate the oxygen-starved tissue. PTMR is generally used for the treatment of severe, end-stage coronary disease.
Another catheter-based procedure used to promote angiogenesis involves gene therapy. For this procedure, genetic material is delivered directly to the diseased area of the body via a catheter. In particular, genetic material, such as Vascular Endothelial Growth Factor (VEGF), is incorporated into gene delivery vehicles called vectors, which encapsulate therapeutic genes for delivery to the diseased cells. Many of the vectors currently in use are based on attenuated or modified versions of viruses. The vectors may also be synthetic versions in which complexes of DNA, proteins, or lipids are fonned into particles capable of efficiently transferring genetic material. A needle injection catheter is used to deliver the vectors containing the genetic material to the appropriate cells of the patient in a safe and efficient manner.
PTCA and angiogenic procedures are generally performed by inserting a guiding catheter into the artery of the patient and advancing the distal end of the catheter to the target area. Once the catheter is positioned at the target area, fluids are then delivered to the target site, i.e. diseased tissue. The term xe2x80x9cfluid(s),xe2x80x9d as used herein, refers to all drugs, genetic materials, growth factors, angiogenic substances, therapeutic agents/substances, diagnostic agents/reagents and other similar chemical/biological agents, including combinations thereof, used to treat and/or diagnose restenosis, thrombosis, angiogenesis and related conditions.
The above-described devices and methods for treatment of cardiovascular disease, and other similar diseases and conditions not specifically described, offer many advantages to potential users. However, it has been discovered that such devices and methods may be deficient in their current fluid-delivery characteristics. A potential drawback is the inability to deliver fluid directly to the target site due to the plaque or diseased tissue barrier in the artery. Although the venous coronary system has been proposed as one of the routes for local fluid delivery to the ischemic myocardium and diseased arterial walls, blood flow direction presents a challenge. Since the direction of blood flow in the venous system is opposite to that in the arterial system, the use of contrast medium does not help to navigate the vasculature as it does so on the arterial side. Further, the location of the venous system also presents an obstacle to accurately positioning the delivery device close to the targeted arterial site.
In view of the above, it is apparent that there is a need to provide a fluid delivery device offering improved fluid delivery features. There is also a need to provide a method of using such an improved fluid delivery device that is convenient, efficient and cost effective. It is also desirable that the catheter-based fluid delivery device be used in combination with intravascular ultrasound (IVUS) technology for accurately mapping the location and distance of various structures in the body of the patient.
In accordance with various aspects of the present invention, an apparatus or device is capable of delivering a drug directly to a target site comprising a main body portion and a secondary body portion. Housed within the elongated, tubular main body portion, having a distal end and a proximal end, are a retractable ultrasound component, a guide wire lumen, one or more fluid lumen and a balloon. The retractable ultrasound component has a transducer located near the distal end of the main body portion. The guide wire lumen is configured to slidably receive a primary-guide wire therein. Further, the balloon is attached near the distal end of the main body portion and is in fluid communication with the fluid lumen. The flexible, secondary body portion of the drug delivery device has a secondary-guide wire having a proximal end and an ultrasonic opaque component located at a distal end of the secondary-guide wire. The secondary-guide wire is in signal communication with the retractable ultrasound component of the main body portion.
The invention also relates to a method of positioning a drug delivery device near a target site. The method includes an act of providing a drug delivery device having a secondary guide wire and a main body portion. The secondary guide wire is inserted into a first lumen of a patient and guided to a target area. An ultrasonic opaque portion, located at the distal end of the secondary guide wire, is positioned near the target site. The main body portion of the device is inserted into a second lumen of a patient or adjacent to the secondary guide wire. A real time image generated from ultrasound signals from the secondary body portion and the main body portion are processed and displayed on an IVUS system. Using these signals, the main body portion is navigated to a location in the target area nearest the ultrasonic opaque portion. The main body is then positioned at a site in the second lumen closest to the target site in the first lumen using the ultrasound signals.
In an alternate embodiment, the method further includes delivering a drug directly to a target site. In this embodiment, the main body portion includes a retractable needle. Once the device is located near the target site, as previously described, the retractable needle is extended from the main body portion so that the needle penetrates the target site. The drug is then dispensed directly into the target site using the retractable needle. The method allows needle position to be precisely determined, both in relationship to the device as well as the target site for drug delivery. This allows accurate delivery of drug to the target site and, thus, enhanced treatment capabilities.